Ultimate Guitar Repair » Blog Archive

Crack Alignment Jig

February 21st, 2010

Crack Alignment Jig:
This is a jig that my father used more than 25 years ago. All you need to make one is a small scrap of hardwood, and an old single (not ganged) tuning machine. I prefer the old vintage style open geared tuning machine because they are much lighter and less bulky.

The usual method of crack repair for a long crack that has sprung out of shape is to remove the back or top plate, align the crack and re-glue the plate back on the instrument. With this handy little jig you can make all crack repairs from the outside and through the sound-hole of the guitar, saving a lot of time and money for your client or yourself.

What You Can Use This Tool For:
This jig is a real aid for alignment of cracks that are in the top, back or side plates of the guitar. Often the wood on each side of the crack becomes miss-aligned for various reasons, such as wood movement due to moisture conditions or stresses within the guitar that have caused the crack to become lifted on one side or the other.

Crack Alignment Jig Drawing
Source: Repair Tools and Jigs

How To Make The Jig:
This is really a very easy jig to make. Start with a block of scrap of hardwood and cut it square on the Table Saw or the Band Saw to the dimensions shown on the diagram above.

Tip: While you are at it, make about four of these jigs as you will need them on some jobs. This also allows you to mill a longer piece of wood, which is much easier and safer than a short one. When you work on an “assembly line” type of job like this you can make 4 of these jigs in just a bit more time than 1 of them.

Once you have the block of wood squared up. Cut the holes for the tuning machine posts. Next cut the center channel donw the center of the block with a table saw or router.

The next step is to cut the outboard leg on the jig down to the center-point of the tuner post. I would now knock off the corners of the jig to keep from injuring the guitar you are working on.

Cut the (4) jigs to length.

Drill the holes for the “E” string to penetrate the jig in the bottom of the jig channel.

Mount the tuning machine on the jig, make the block used at the ball end of the string and you are all set.

Get Free PDF Plan Of This Jig:
If you would like a full size drawing in PDF format of this jig just follow the link for the Crack Alignment Jig.

Use of This Tool:
We will be publishing a an article on Crack Alignment Jig Use. Watch for that shortly.

The Last Word:
Do you have a favorite tool or trick you would like to share with the community. We would appreciate hearing about it. Also feel free to offer any advice or improvements to my articles.